Catalytic production of light olefins rich in propylene

Abstract

A hydrocarbon feed containing C 4- C 7 olefins and/or paraffins is converted to light olefins, by contacting the feed with a catalyst containing ZSM- 5 and/or ZSM- 11, having an initial silica to alumina ratio greater than about 300:1, and phosphorus.

We claim:  
     
       1. A process for converting hydrocarbon feed which includes C 4 -C 7  olefins and C 4 -C 7  paraffins to a product which includes ethylene and propylene, said process comprising: 
       contacting said feed with a catalyst which comprises ZSM-5, ZSM-11 zeolites or combination thereof, having an initial silica/alumina ratio greater than 300:1, and phosphorus under sufficient conditions to convert C 4 -C 7  paraffins and C 4 -C 7  olefins in said hydrocarbon feed to ethylene and propylene.  
     
     
       2. The process of claim  1  wherein the zeolite makes up about 5 to 75 wt. % of the catalyst, a matrix material makes up about 25 to about 95 wt. % of the catalyst and the phosphorus is present in an amount of about 0.5 to 10 wt. % of the catalyst. 
     
     
       3. The process of claim  2  wherein the matrix material is selected from the group consisting of silica, alumina, silica-alumina, clay and mixtures thereof. 
     
     
       4. The process of claim  1  wherein said contacting is carried out in a dense fluidized bed reactor or a fixed-bed swing reactor. 
     
     
       5. The process of claim  1  wherein said conditions comprise a temperature from about 950° F. to about 1300° F., a pressure from about 2 to about 115 psia, a catalyst/hydrocarbon feed weight ratio from about 0.1 to about 10, and a WHSV from about 1 to about 20 hr −1 . 
     
     
       6. The process of claim  1  wherein the product comprises propylene and ethylene, with a C 3 =/C 2 =weight ratio greater than 3, and a C 3  fraction containing greater than 80 wt. % propylene. 
     
     
       7. The process of claim  5  wherein the product has a (C 2 =+C 3 =)/BTX weight ratio greater than 3.5, based upon a net increase in C 2 =, C 3 =and BTX relative to the feed. 
     
     
       8. The process of claim  6  wherein the product comprises ethylene plus propylene in an amount greater than 20 wt. % based on total product. 
     
     
       9. The process of claim  6  wherein the product contains less than about 10 wt. % ethane plus propane. 
     
     
       10. The process of claim  1  wherein said 
       contacting of said feed with said catalyst is carried out in a dense fluidized bed reactor under reaction conditions to produce a product effluent comprising propylene and ethylene; and further comprising:  
       a. separating the effluent and the catalyst, said catalyst containing coke;  
       b. regenerating the catalyst containing coke by contact with oxygen-containing gas to produce hot, regenerated catalyst; and  
       c. recycling the hot, regenerated catalyst to the fluidized bed reactor.